Effect of different acidic or alkaline environments on structural characteristics, functional and physicochemical properties of lentinus edodes protein

Abstract

This study aimed to investigate the structural characteristics, functional, physicochemical properties of lentinus edodes protein (LEP) at acidic or alkaline environments. Structural characteristics of LEP were evaluated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fourier transform infrared spectroscopy (FTIR), free sulfhydryl groups, zeta potential, intrinsic fluorescence, surface hydrophobicity, particle size distributions. Physicochemical properties of LEP were characterized by solubility, foaming properties, emulsifying properties, water holding capacity (WHC), fat adsorption capacity (FAC), thermal denaturation temperatures. SDS-PAGE showed LEP had seven bands of 52.48, 39.63, 27.93, 24.59, 23.50, 18.28, 17.06 kDa, in which two main bands were 24.59, 52.48 kDa. The sum content (57.87%, 54.10%) of α-helix and β-sheet at pH 3.0, 4.0 was higher than those (39.85%, 37.95%) at pH 7.0, 9.0. LEP had higher solubility, surface hydrophobicity, free sulfhydryl, zeta potential, better foaming capacity, emulsion activity index far away from pH 4.0, while had lower fluorescence intensity (1171 A.U.), larger particle size (1990 nm), better foaming stability, emulsion stable index at pH 4.0. The denaturation temperatures (81.61 °C, 81.84 °C) of LEP at pH 3.0, 4.0 were higher than those (78.62 °C, 74.93 °C) at pH 7.0, 9.0. These results provide fundamentals for LEP as food ingredient to be employed in food industry.